Hi Guys..... Long time no see!

I have what sounds like a standard "tune-up" problem.

My EB use to race up hills etc, and have reasonable power, but over the last six months or so, its got noticably weak, to the point where climbing a medeocre hill after stopped at lights is embarrasing!

I've done the standard stuff: changed the plugs, leads, checked timing, changed filters etc, but i'm scratching my head as to whats the problem. Thought it was the transmission or torque converter, but I changed them on the weekend (as they had other issues and needed changing anyway).

Heres the interesting bit. I haven't looked at how the EEC-IV changes the timing in a few years. From memory, the more you accelerate and demand power, the more it sghould advance the timing, is this correct?

Why I ask, is that when I put the light on it with a small amount of throttle, it sits on -10 BTDC, but when you floor it, it only seems to move back to around -18 BTDC, and only that descrete value - nothing in between. Is this correct? I had a map sensor code pop up too, so I straight away thought "AHA!" (the vacuum hose was cracked). I replcaced it and reset the codes, but it made no change to the timing.

I wouldn't mind knowing how the timing is supposed to behave in a "normal" EB, so I can determine if i should start looking at the TFI or (gulp!) the EEC

Any help appreciated!

oops. forgot another tidbit of info. Is it true that spark colour is an indication of ignition power? (blue/yellow), and can this drastically effect power?

I heard thru a friend of a guy of a mate that a yellow spark means somewhere along the line something is breaking down, and the mixture doesn't burn as easily. Sounds correct, but can it have such a major impact on acceleration?

Cheers again!